Problem: $\dfrac{4}{10} + \dfrac{16}{100} = {?}$
Answer: The fractions must have the same denominator before you can add them. Rewrite $\dfrac{4}{10}$ as $\dfrac{40}{100}$ $\dfrac{40}{100} + \dfrac{16}{100} = {?}$ $ = \dfrac{56}{100}$